CN104190930A - Laser additive manufacturing method for homogeneous functionally graded material and structure - Google Patents

Abstract

The invention relates to a method for laser additive manufacturing of homogeneous functionally graded materials and structures. The method includes the following steps: mapping different functions to different temperatures, and applying different temperatures as boundary conditions to different parts of a three-dimensional model , use the three-dimensional finite element method to calculate the heat conduction equation of the model, and obtain the internal temperature gradient distribution, that is, the temperature field of the model; extract the isothermal surface of the model to obtain a set of surfaces with different temperature marks; The contour of the intersection line of the surface, that is, the plane isotherm; process the single-layer slice to obtain the scanning path of the single-layer laser parameter with a gradient change; repeat the steps until the slice is completed to obtain the laser scanning path of the model; input the generated laser scanning path to A laser 3D printer controls the additive manufacturing process to obtain homogeneous functionally graded structures. This method can additively manufacture homogeneous functionally graded materials and structures, which cannot be achieved by current laser additive manufacturing methods.

Description

A laser additive manufacturing method for homogeneous functionally graded materials and structures

technical field

The invention belongs to the technical field of laser additive manufacturing, and relates to a laser additive manufacturing method for homogeneous functionally graded materials and structures.

Background technique

From the perspective of material structure, functionally graded materials refer to selecting two (or more) materials with different properties, and continuously changing the composition and structure of the two (or more) materials to make the interface disappear and lead to material The performance of the material changes slowly with the composition and structure of the material. At present, typical functionally graded materials such as Ti/Al2O3 are composed of two materials, Ti and Al2O3. It has good heat resistance, heat insulation, high strength and high temperature oxidation resistance of Al2O3 ceramics.

Currently, laser stereolithography (LENS) can be used to additively manufacture functionally graded materials and structures. However, all the current reported literature or patents use two or more materials to additively manufacture functionally graded materials or structures.

Homogeneous metal or ceramic materials are required to show a gradient change in function during application, that is, the metallographic structure, grain size and orientation of the same material gradually occur according to the requirements of functions (such as hardness, strength, stiffness, density, etc.) Slowly changing to form a functional gradient structure. In fact, almost all industrial or natural structures have this characteristic, such as gears that are soft on the inside and rigid on the outside, the extremely hard tooth surface is used to resist the contact impact stress of the tooth surface, and the softer gear core is used to reduce the vibration of the gear ; Such as bone, the high-density cortical bone distributed on the surface of the bone has strong resistance to compression and distortion, and the low-density cancellous bone distributed inside stores the bone marrow. However, this type of industrial structure is usually obtained by special heat treatment, nitriding, carburizing, etc. after machining (subtractive manufacturing, such as turning, milling, planing, etc.). Such natural structures are the product of long-term evolution.

At present, laser additive manufacturing technology can only produce gradient functional materials and structures with multi-material components, or can only produce homogeneous structures without performance gradients. Since the laser additive manufacturing technology has the characteristics of net shape or near net shape, it can manufacture geometrically and topologically complex structures, so it is of great significance to find a laser additive manufacturing method for homogeneous functionally graded materials and structures.

Contents of the invention

In view of this, the object of the present invention is to provide a laser additive manufacturing method for homogeneous functionally graded materials and structures, which can overcome the problem that the existing laser additive manufacturing technology cannot manufacture homogeneous functionally graded materials and structures.

To achieve the above object, the present invention provides the following technical solutions:

A laser additive manufacturing method for homogeneous functionally graded materials and structures, comprising the following steps: Step 1: Mapping different functions to different temperatures, applying different temperatures as boundary conditions to different parts of the three-dimensional model S0, Use the three-dimensional finite element method to calculate the heat conduction equation of the model S0, and obtain the internal temperature gradient distribution, that is, the temperature field S1 of the model S0; Step 2: Extract the isothermal surface of the model to obtain a surface set S2 with different temperature marks; Step 3: Align the curved surface The set S2 is sliced to obtain the contour of the intersection line between each layer and the isothermal surface, that is, the plane isotherm S3; Step 4: Process the single-layer slice to obtain the scanning path S6 with a gradient change in the laser parameters of the single layer; Step 5: Repeat the steps Step 3 and Step 4, until the slicing is completed to obtain the laser scanning path S7 of the model; Step 6: input the generated laser scanning path to the laser 3D printer to control the additive manufacturing process, and obtain a homogeneous functionally graded structure S8.

Further, in Step 4, the processing of the single-layer slices specifically includes the following steps: 1) Extracting adjacent isotherms in the plane isotherm S3 to construct inner and outer rings, and geometrically forming the inner and outer rings in the area surrounded by the inner and outer rings. Scanning path S4; 2) The same laser process parameters are given to the scanning path S4 generated by the area surrounded by the same temperature isotherm to obtain the laser scanning path S5; the scanning path S4 generated by the area surrounded by different temperature isotherms Give different laser process parameters, that is, adjust the laser process parameters according to the temperature gradient so that it changes in a gradient, so that the function of its mapping also changes in a gradient; 3) Repeat steps 1) and 2) until the single-layer plane isotherm is processed , to obtain a scanning path S6 in which the single-layer laser parameters change in a gradient manner.

Further, the materials include metals and ceramics, wherein metals include steel, aluminum alloys, titanium alloys and high-temperature alloys, etc., and ceramics include alumina, zirconia, silicon carbide, etc.

Further, the functions include hardness, rigidity, strength, toughness and the like.

Further, the laser additive manufacturing method includes laser selective sintering (SLS), laser selective melting (SLM) and laser stereolithography (LENS); the laser parameters include: laser power, exposure time, point pitch, row pitch, Scan speed and spot diameter.

Further, the laser power is 0.1 mW-10 kW, the exposure time is 0.001 ms-30 s, the spot pitch is 0.1 um-200 um, and the line pitch is 0.1 um-400 um.

The beneficial effects of the present invention are: the method adopted in the present invention can overcome the problem that the existing laser additive manufacturing technology cannot manufacture homogeneous functionally graded materials and structures, and can additively manufacture homogeneous functionally graded materials and structures, which is currently Laser additive manufacturing methods can not do.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is a schematic flow chart of the method of the present invention.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Figure 1 is a schematic flow chart of the method of the present invention, as shown in the figure, the laser additive manufacturing method of the present invention includes the following steps: Step 1: Map different functions to different temperatures, and use different temperatures as Boundary conditions are applied to different parts of the three-dimensional model S0, and the heat conduction equation of the model S0 is calculated using the three-dimensional finite element method to obtain the internal temperature gradient distribution, that is, the temperature field S1 of the model S0; Step 2: Extract the isothermal surface of the model to obtain The temperature-marked surface set S2; Step 3: Slice the surface set S2 to obtain the contour of the intersection line between each layer and the isothermal surface, that is, the plane isotherm S3; Step 4: Process the single-layer slice to obtain the single-layer laser parameters. Gradient scanning path S6; step five: repeat steps three and four until the slicing is completed to obtain the laser scanning path S7 of the model; step six: input the generated laser scanning path to the laser 3D printer to control the additive manufacturing process, and obtain the same Mass-functional gradient structure S8.

Wherein, in step 4, the processing of the single-layer slices specifically includes the following steps: 1) Extracting adjacent isotherms in the plane isotherm S3 to construct an inner and outer ring, and forming a geometric shape in the area surrounded by the inner and outer rings. Scanning path S4; 2) The same laser process parameters are given to the scanning path S4 generated by the area surrounded by the same temperature isotherm to obtain the laser scanning path S5; the scanning path S4 generated by the area surrounded by different temperature isotherms Give different laser process parameters, that is, adjust the laser process parameters according to the temperature gradient so that it changes in a gradient, so that the function of its mapping also changes in a gradient; 3) Repeat steps 1) and 2) until the single-layer plane isotherm is processed , to obtain a scanning path S6 in which the single-layer laser parameters change in a gradient manner.

In this embodiment, the material includes metal and ceramics, wherein the metal includes steel, aluminum alloy, titanium alloy, and superalloy, etc., and the ceramic includes alumina, zirconia, silicon carbide, and the like. Said functions include hardness, rigidity, strength, toughness and the like. The laser additive manufacturing method includes laser selective sintering (SLS), laser selective melting (SLM) and laser stereolithography (LENS); the laser parameters include: laser power, exposure time, point pitch, line pitch, scanning speed and spot diameter, wherein, the laser power is 0.1mW-10kW, the exposure time is 0.001ms-30s, the spot pitch is 0.1um-200um, and the line spacing is 0.1um-400um.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (6)

1. a laser gain material manufacture method for homogeneity FGM and structure, is characterized in that: comprise the following steps:

Step 1: be different temperature by different functional mappings, using different temperature as boundary condition, be applied to respectively the different parts of threedimensional model S0, utilize the equation of heat conduction of three dimension finite element method model S0, obtain inner temperature gradient distribution, be i.e. the temperature field S1 of model S0;

Step 2: the isothermal level of extraction model obtains the curved surface S set 2 with different temperatures mark;

Step 3: curved surface S set 2 is cut into slices, obtain every layer of the intersection profile with isothermal level, i.e. plane thermoisopleth S3;

Step 4: monolayer slices is processed, obtained the scanning pattern S6 that individual layer laser parameter changes in gradient;

Step 5: repeating step three and step 4, obtain the laser beam scan path S7 of model until cut into slices;

Step 6: the laser beam scan path of generation is input to laser 3D printer and controls increasing material manufacture process, obtain homogeneity function gradient structure S8.

2. the laser gain material manufacture method of a kind of homogeneity FGM according to claim 1 and structure, is characterized in that: in step 4, described processes specifically and comprise the following steps monolayer slices:

1) in plane thermoisopleth S3, extract adjacent thermoisopleth structure inner and outer ring, and the region surrounding at inner and outer ring becomes scanning pattern S4 how much;

2) the scanning pattern S4 region being surrounded by the identical thermoisopleth of temperature being generated gives identical laser technical parameters, obtains laser beam scan path S5; The scanning pattern S4 that the region being surrounded by the different thermoisopleths of temperature generates gives different laser technical parameterses, according to thermograde, changes adjustment laser technical parameters it is changed in gradient, and the function of its mapping is also changed in gradient;

3) repeating step 1) and 2), until individual layer plane thermoisopleth is disposed, obtain the scanning pattern S6 that individual layer laser parameter changes in gradient.

3. the laser gain material manufacture method of a kind of homogeneity FGM according to claim 1 and structure, is characterized in that: described material comprises metal and pottery.

4. the laser gain material manufacture method of a kind of homogeneity FGM according to claim 1 and structure, is characterized in that: described function comprises hardness, rigidity, intensity, toughness.

5. the laser gain material manufacture method of a kind of homogeneity FGM according to claim 1 and structure, is characterized in that: described laser gain material manufacture method comprises selective laser sintering, the melting of laser constituency and laser solid forming; Described laser parameter comprises: laser power, time for exposure, some distance, line-spacing, sweep speed and spot diameter.

6. the laser gain material manufacture method of a kind of homogeneity FGM according to claim 5 and structure, it is characterized in that: described laser power is 0.1mW～10kW, time for exposure is 0.001ms～30s, and point is apart from being 0.1um～200um, and line-spacing is 0.1um～400um.